Self-injury is common in autism spectrum disorder (ASD); however few studies have investigated correlates of self-injury or the putative associations with self-restraint. Questionnaire data on self-injury, self-restraint, health conditions, overactivity/impulsivity and repetitive/restricted behavior were collected on 208 children and 216 adults with ASD (mean age = 24.10, range 6–61). Self-injury and self-restraint were frequent and significantly associated in both children (45.7% and 40.9%, p < 0.001) and adults (49.1, and 42.6%, p < 0.001). Severe self-injury was predicted by lower ability, health conditions and overactivity/impulsivity in children (p < 0.001) and repetitive/restricted behavior and overactivity/impulsivity in adults (p < 0.001). These data provide preliminary support for a developmental model of self-injury and self-restraint in which painful health conditions and compromised behavioral control influence the presence and trajectory of self-injury in ASD.